There is a need for the improved detection of a wide variety of analytes. Specific analytes for which there is a critical testing needed include pathogenic agents and microbes. Broad clinical use of such a system would assist in identifying diseases or serious illnesses, greatly assisting physicians in diagnosis.
Improved detection is also needed in agriculture and food production, as well as a means to detect contamination, spoiling, or poisoning of food. Food includes for example, items such as drinking water and fruit juices.
In one example, pathogenic bacteria, such as Escherichia coli (E. coli), can contaminate food and beverages, causing infection outbreaks with serious consequences. The Centers for Disease Control and Prevention (CDC) estimates that 73,000 cases of E. coli infection occur annually in the United States. Over 2,000 people are hospitalized every year and over 60 people die as a direct result of E. coli infections and resulting complications.
In developing countries and localities of poor sanitation, the threat of E. coli is even more severe. One potential reason for the outbreaks is the absence of adequate food and water testing before public consumption. Currently, clinical detection of pathogenic bacteria often relies on culturing the bacteria from a suspected contaminated sample, which can take several days. As such, there is a pressing need for the development of rapid, convenient and sensitive techniques for pathogen detection.
Many pathogens use human cell surface carbohydrates as anchors to facilitate their attachment, which subsequently results in infection. For instance, influenza viruses bind with epithelial cell surface sialic acid in the respiratory tract, while E. coli is known to recognize mannose and galactose. In addition, one challenging aspect of studying carbohydrate and pathogen interaction is the low affinity of oligosaccharides to their protein receptor(s). Increasing the valency of an oligosaccharide ligand by simultaneously involving multiple copies of the oligosaccharide can markedly enhance its affinity towards the receptor.
There is also a need for a system to detect analytes that is not subjected to interference from clutter and/or near neighbor molecules. There is also a need for the system to have a low cost, low false alarms and high probability of detection. There is also a need to accurately measure amounts of analyte concentrations in the sample being tested.
Also, there is a need in forensic testing, including for example, searching for specific DNA sequences in a sample at the search site. For example, a system is needed to detect biological agents and toxins to provide early alert in case of a terrorist attack.
Further, in many industrial processes, it is desirable to measure and analyze the concentration of trace species in flowing gas streams and liquids with a high degree of speed and accuracy. Such measurement and analysis is required when the concentration of contaminants is critical to the quality of the end product, but may still be desirable even when not required. Such a system would enable leak detection, process control, detection of material degradation, control of concentration, and a host of other process applications in a wide range of industries.
A compact and automated instrument is desired to rapidly detect the presence of such analytes in the field, rather than requiring that samples be sent to a remote, or off-site, location for testing.
Magnetic nanoparticles (MNPs) have been extensively employed in biomedical research for magnetic separation, targeted drug delivery, protein and DNA purification, and contrast enhancement in magnetic resonance imaging (MRI). The detection of MNPs is typically monitored by transmission electron microscopy (TEM), superconducting quantum interference device (SQUID) magnetometry or MRI, which are limited by access to such expensive and cumbersome equipment.
There is, therefore, a need for an efficient and easy to use system for detecting agents in an environment that is not dependent on these expensive cumbersome methods.